package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.apache.tomcat.util.buf.StringUtils;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    @Override
    public Result queryById(Long id) {
        //Shop shop = queryWithPassThrough(id);//缓存穿透
        Shop shop = queryWithMutex(id);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopjason = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopjason)) {
            Shop shop = JSONUtil.toBean(shopjason, Shop.class);
            return shop;
        }
        if (shopjason!=null){
            return null;
        }
        Shop shop = getById(id);
        if (shop == null) {
            stringRedisTemplate.opsForValue().set(key, ""
                    ,CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop)
                ,CACHE_SHOP_TTL, TimeUnit.MINUTES);

        return shop;
    }

    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopjason = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopjason)) {
            Shop shop = JSONUtil.toBean(shopjason, Shop.class);
            return shop;
        }
        if (shopjason!=null){
            return null;
        }
        String lockKey=LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean islock = tryLock(lockKey);
            if (!islock){
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            String shopJson = stringRedisTemplate.opsForValue().get(key);
            if (StrUtil.isNotBlank(shopJson)) {
                shop = JSONUtil.toBean(shopJson, Shop.class);
                return shop;
            }//双重验证
            shop = getById(id);
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(key, ""
                        ,CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop)
                    ,CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unLock(lockKey);
        }

        return shop;
    }//通过互斥锁来解决缓存击穿

    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopjason = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(shopjason)) {
            return null;
        }
        RedisData redisData = JSONUtil.toBean(shopjason, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())) {
            return shop;
        }//未过期
        String lockKey=LOCK_SHOP_KEY+id;
        boolean islock = tryLock(lockKey);
        if (islock){
            RedisData redisData1 = JSONUtil.toBean(shopjason, RedisData.class);
            JSONObject data1 = (JSONObject) redisData.getData();
            Shop shop1 = JSONUtil.toBean(data, Shop.class);
            LocalDateTime expireTime1 = redisData.getExpireTime();
            if (expireTime1.isAfter(LocalDateTime.now())) {
                return shop;
            }//未过期,双重验证
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });

        }
        return shop;
    }//逻辑过期解决缓存击穿

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }//尝试获取锁

    private void unLock(String key){
        stringRedisTemplate.delete( key);
    }//释放锁

    public void saveShop2Redis(Long id,Long expireSeconds){
        Shop shop = getById(id);
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }//缓存预热

    @Override
    @Transactional
    public Result Update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        updateById( shop);//先更新数据库
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());//再更新缓存
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        if (x == null || y == null) {
            Page<Shop> shopPage = query().eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(shopPage.getRecords());
        }
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key
                        , GeoReference.fromCoordinate(x, y)
                        , new Distance(5000)
                        , RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> List = results.getContent();
        List<Long> ids=new ArrayList<>(List.size());
        Map<String,Distance> distanceMap=new HashMap<>(List.size());
        List.stream().skip( from).forEach(geoResult -> {
            String idStr = geoResult.getContent().getName();
            ids.add(Long.valueOf(idStr));
            Distance distance = geoResult.getDistance();
            distanceMap.put(idStr,distance);
        });
        if (!ids.isEmpty()) {
            String idListString = StrUtil.join(",", ids);
            List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idListString + ")").list();
            for (Shop shop : shops) {
                Double distance = distanceMap.get(shop.getId().toString()).getValue();
                shop.setDistance(distance);
            }
            return Result.ok(shops);
        } else {
            // 如果没有ID，返回空列表
            return Result.ok(new ArrayList<Shop>());
        }
    }
}
